A. Field of the Invention
The present invention relates to agitation control for a washing machine, and in particular, to user-selectable agitation action and speed.
B. Problems in the Art
Modern washing machines usually employ a number of functional features. This includes a variety of washing regimes (e.g. regular, permanent press, soak only). Most machines include user-selectable controls allowing the user to set the machine differently for different washing tasks, action, or regimes. For example, selection of a “regular” washing regime usually indicates a longer wash cycle, and relatively substantial wash action (e.g. faster agitation and spin speeds). Another example is a delicate or permanent press regime, which usually indicates shorter wash cycle and less wash action (e.g. slower agitation).
It has been found to be desirable to have different agitation robustness for different washing tasks. By selection between pre-programmed wash regimes or cycles, the user has some control over the gentleness or robustness of mechanical wash action. The user usually selects the type of washing regime, and the machine automatically follows a pre-programmed wash action for that regime. The user normally does not have control over washing action other than washing regime selection.
One way different washing or agitation action is created in an automatic washing machine is by utilizing a multi-speed electric motor that can rotate or reciprocate an agitation impeller (also sometimes referred to as the agitator) at different speeds. One specific example is U.S. Pat. No. 3,474,646. The user operates a control knob to select between three discrete agitation speeds from a three speed (high, medium, and low speed) motor, regardless of which washing cycle or regime is selected from a separate control. While this provides three agitation speed choices for the user, independent of washing cycle, it is generally the case that the more speeds of a motor, the higher the cost and complexity.
Another approach is to vary what might be called the “duty cycle” of agitation. In other words, the machine allows the user to select cumulative agitation robustness over a standard period of time. This can be accomplished, e.g., by dividing the standard period of time into alternating sub-periods of different agitator impeller speeds or by lengthening or shortening cumulative duration of agitation. The amount of energy imparted to the clothes by the impeller during the period is a function of the average impeller speed during the period. One example of this is U.S. Pat. No. 3,589,148.
A still further solution was suggested by the owner of the present application. In an embodiment described in U.S. Pat. No. 6,025,682 (“the '682 patent”), the user is presented with four different agitation options. First is “continuous fast”, meaning the faster speed of a two speed motor is continuously applied to the impeller during an agitation period. The second is “continuous slow”, meaning the slower speed of the two-speed motor is continuously applied to the impeller during the agitation time. A third can be called “intermittent fast”, and in the '682 patent comprises sub-periods of alternating fast and slow agitation speed of the impeller during an agitation period. During that period, the agitation speed, on average, would be considered intermediate between fast and slow; thus, not only a different type of agitation, but also a third “speed”. The fourth is referred to as “intermittent slow”, comprising alternating sub-periods of slow agitation and no agitation. On average, over the agitation period, this is both a different type of agitation and a fourth “speed”; slower than continuous slow.
Additionally, in the '682 patent, a user can adjust the agitation duty cycle in either intermittent fast or intermittent slow regimes. The user can infinitely variably adjust, within a range, duration of sub-periods of differing impeller speed. An example would be, in intermittent fast mode, lengthening sub-periods of fast agitation, which would shorten sub-periods of slow agitation; which would mean the average speed over the entire agitation period becomes closer to “continuous fast”. Conversely, sub-periods of fast could be shortened, which would lengthen sub-periods of slow; resulting in an average speed over the entire period closer to “continuous slow”. In other words, the user could select longer sub-periods of fast agitation and shorter periods of slow agitation in “intermittent fast” mode, or vise versa; and select longer sub-periods of slow agitation and shorter periods of no agitation, or vise versa, in the “intermittent slow” mode, over a range of values, giving a range of different “average” speeds between continuous fast or continuous slow respectively.
As is well known in the art, present washing machines generally are pre-programmed or pre-designed to follow a sequence of functions during any selected washing regime. The agitator is operated only at certain times of most regimes. As described, the '682 patent allows for user-selectability of speed and/or duty cycle of agitation at the times agitation occurs, including two settings with infinitely variable adjustability within the setting. Thus, with infinitely variable adjustability, in either intermittent fast or intermittent slow agitation speed selection, the user has an additional manually adjustable control that can alter agitation speed over a range of speeds within that general class of speed (i.e. intermittent fast or intermittent slow). For example, if intermittent fast is selected, which averages to a medium speed, the user can also infinitely variable adjust the speed between higher intermittent fast and slower intermittent fast.
Thus, using just a two-speed motor, the '682 patent provides four different agitation “speed” options from which the user can manually select. Thus, the user can in a sense “override” or dictate the robustness of the washing action, regardless of which washing regime or cycle is selected, by a selection from continuous fast, intermittent fast, continuous slow and intermittent slow agitation speeds from a manually operated control on the washing machine control panel.
The '682 patent accomplished this infinite variability by utilizing a variable resistor, manually controlled by the user from the control panel, as the mechanism for allowing infinitely variable selectivity of a duty cycle (how long or short the sub-periods of fast, slow or no agitation are) in the two intermittent modes. It also includes a microprocessor controlled timer circuit, which is used by the system to know where the washing machine is in any given regime of washing, and a microprocessor controlled two-relay switch to create the intermittent periods in the intermittent modes; i.e. switch the motor between fast and slow or slow and no agitation.
The '682 patent is one way to give the user more choices and expanded control of agitation. Although the solution of the '682 patent works well for its intended purpose, it is believed there may be room for improvement in this area because of a combination of factors. Although providing substantial user-control of and options for washing action and providing more than two agitation “speeds” from a two-speed motor, the microprocessor-controlled dual relays and timer circuit and the variable resistor add significant cost to the machine. The cost may not justify the amount of user-selectable options offered by the '682 patent solution.
Therefore, it is believed that there is room for improvement in the art for an alternative way to provide expanded user-controlled agitation in a more economical way.
It is therefore a principle object of the present invention to provide a beneficial method of agitation control. Other objects, features, or general advantages of the present invention can include:                1. increased options for wash action by economical means;        2. increased options for wash action without using microprocessor or electronic technology;        3. increased options for wash action utilizing an electromechanical timer circuit;        4. economy;        5. efficiency;        6. durability;        7. relatively non-complex structure and method;        8. ease of user selectability; and        9. flexibility and adaptability for different pre-designed wash action regimes.        
These and other objects, features, and advantages of the present invention will become more apparent with reference to the accompanying drawings and claims.